Electric protective system



Aug. 17, 1937. MOYER 2,090,517

ELEC TRIC PROTECTIVE SYSTEM Filed Aug. 1, 1936 Fig.1.

Invefitor: ElmoEMoyen His Attorney.

Patented. Aug. 17, 1937 PATENT OFFICE 'ELECTRIC PROTECTIVE SYSTEM Elmo E. Moyer, Scotia, N. Y., assignor to General Electric Company, a corporation of New York Application August 1, 1936, Serial No. 93,865

13 Claims.

My invention relates to protective systems and more particularly to an electric protective system for application in connection with high voltage apparatus for preventing a person from ob- 5 taining access to the apparatus as long as the apparatus is subjected to high voltage conditions.

In connection with the operation and inspection of high voltage electric apparatus, it is frequently desirable to provide protective systems to l prevent a person from obtaining access to apparatus subjected to high voltages. Heretofore, the electric protective systems have been concerned with devices and arrangements for effecting interruption of the associated circuit to remove the 7 dangerously high voltages in the event an operator or inspector attempted to obtain access to the apparatus. For example, in connection with apparatus which is enclosed within protective chambers or compartments, it has been usual to 20 provide interlocking arrangements and switching means on the doors to these compartments by means of which the high voltages applied to the apparatus are automatically removed upon movement of the actuati g handle or upon movement of the door itself. It is apparent that in applications using protective apparatus of this nature, it is possible to obtain access to the high voltage apparatus without effecting an interruption of the supply or associated circuit in the event the 30 associated switching means or control circuits become defective. In view of these features, there has been evidenced a decided needfor protective apparatus for high voltage systems in which it is i made impossible for a person to obtain access to the apparatus when a high voltage is impressed on the apparatus.

It is an object of my invention to provide a new and improved electric protective system.

It is another object of my invention to provide 4: a new and improved electric protective system for high voltage electrical apparatus in which an operator is prevented from obtaining accessto the apparatus when high voltages are impressed on the apparatus. 45 It is a further object of my invention to provide a new and improved protective system for electrical apparatus whereby the voltage of the apparatus must be of. a value below a predetermined value to permit access to the apparatus.

50 In accordance with the illustrated embodiment of my invention, I provide a new and improved protective system for high voltage electrical apparatus. For the purposes of explanation, I have chosen to represent my invention as applied to 55 an electric valve translating system in which electric valve means are housed within separate enclosures, chambers or compartments. Each chamber is provided with a door through which access may be obtained to inspect or replace the several electric valve means. An operating mech- 5 anism is associated with each door whereby the door may be opened in the event the voltage impressed on the electric valve means is below a predetermined value- When the electric valve means is in operation and when the voltage impressed on the electric valve means is above the predetermined value, the operating mechanism associated with the door is rendered ineffective by a latch which maintains the door closed. There is also associated with the operating mech- 1 anism a circuit for testing the voltage impressed on the electric valve means. If the voltage on the electric valve means is below the predetermined value, the operating mechanism may be moved to open the door. This testing operation must be performed and the voltage condition satisfied before access may be obtained to the electric valve means.

For a better understanding of my invention, reference may be had to the following description taken in connection with the accompanying drawing and its scope will be pointed out in the appended claims.

Fig. 1 of the accompanying drawing diagrammatically represents my invention as applied to a protective system for an electric valve translating system, and Fig. 2 is a diagrammatical representation of the circuit associated with each of the electric valve meansof the translating circuit shown in Fig. 1. 7

Referring now to Fig. 1 of the accompanying drawing, my invention is diagrammatically illustrated as applied to an electric valve translating 7 system for transmitting energy between an alternating current circuit I and a direct current load circuit 2 which may be provided with a ground connection 3. Interconnecting the alternating current circuit I and the load circuit 2 there is provided a circuit interrupter d, a transformer 5, and electric valve means 6, 1 and 8, preferably of the type employing an ionizable medium such as a gas or a vapor. The electric valve means, 6, I, and 8, are housed within separate chambers or compartments 9, I0, and II, respectively. While I have shown my invention as applied to an I electric valve means employing a plurality of separate electric valve means each having a single anode and a single cathode, it should be understood that I may employ electric valve means 55 of the .type having a plurality of anodes and a single cathode within an enclosing receptacle.

The chambers 9, l9, and M are provided with doors l2, l3 and it, on each of which there is 5 mounted any suitable operating mechanism such as a handle i5. In order to maintain the doors l2, l3 and iii in the closed position to prevent access to the electric valve means when the voltage of the apparatus is above a predetermined value, I provide any suitable latch mechanism, such as the latch I6, which is retained in the locked position by any suitable control or relay means, such as the electroresponsive device ll. Referring now to Fig. 2 of the accompanying l5' drawing where the protective system is shown more in detail, the electric valve 6 is considered to be housed within the chamber 9 and the line A represents the right-hand vertical edge of the door i2, and corresponding elements referred 0 to in Fig. 1 are assigned like reference numerals.

The handle it is provided with an extension 93 which is employed to engage the latch member it to rotate the latch member l3 counterclock- 2 wise to permit the door to be opened when the value. Connected to the operating handle 65 and operated thereby, I provide a switch mechanism including movable contacts l9 and 29, insulating segments 2i, and stationary contacts 22 and 23. In the particular arrangement of the operating mechanism and the associated switch mechanism, I have shown the switch mechanism as being constructed tohave an initial position shown in Fig. 2, an. intermediate position in which the movable contacts l9 and 29 are made to engage stationary contacts 22 and 233, respectively, and a final position in which the extension it of the operating mechanism l5 engages the latch member l6 and rotates this means counterclockwise to permit the door to be opened.

To provide a means for effecting release of the latch member it when the voltage of the apparatus is below a predetermined value, I have employed any suitable means, such as an electromagnetic device 2 arranged to be responsive to current of a predetermined minimum value. A spring biased detent member 25 is associated with the current responsive means 26 to control the position of the detent member to permit the latch member It to be moved by the operating handle I5. Normally, the detent member 25 is biased to the position shown in Fig. 2 to maintain the latch member IS in the locked position.

Any suitable source of current, such as the alternating current circuit 26 may be employed to energize the current responsive means 24.

Interposed between the current responsivemeans 2 4 and the alternating current circuit 26, I employany current controlling means such as a 0 variable impedance device 21 including a primary winding 28 which is connected in series relation with the current responsive device 24, and a secondary winding 29 which is employed to control the resultant inductive reactance of the primary 65 winding 29 and hence to efiectr control of the current supplied to the current responsive means In order to provide a means for testing an electrical condition, such as the voltage of the elec-, 7 tricjvalve- 6, prior to the release of the latch member 16, I provide a test circuit 30-.for determining the voltage of the electric valve 6. The test circuit 30 includes two separate parallel branches connected between the electric valve 6 75 and a point of reference potential such as a aoaac 17 1y shown in Figs. 1

voltage of the apparatus is below a predetermined ground connection 3! The upper parallel branch includes a conductor 32, stationary contacts 22 of the switch mechanism, circuit interrupting means as a fuse 33, secondary winding 29 of the current controlling means 21 and the ground connection 3i. The lower parallel branch of the test circuit 30 includes a conductor 3 1, stationary contacts 23 of the switch mechanism, circuit interrupting means such as a fuse 35, and a ground connection 31*. While the means for controlling the secondary parallel branches in accordance with the voltage of the electric valve 9 have been shown as being of the current responsive type such as thermal fusesfit should be understood that I may employ other suitable means such as' electromagnetic devices for efiecting interruption of the parallel branches when the voltage of the electric valve means 6 is above the predetermined value to cause an excess of current to flow through the test circuit.

For the purpose of explaining the operation of the embodiment of my invention diagrammaticaland 2, let it be assumed that the circuit breaker i is in the closed position and that the electric valve means 6,? and 8 are operated to supply direct current to load circuit 2. Under these conditions, the electric valve means 3, l and 8 are subjected to voltages considerably above the ground potential. Let it be further assumed that the alternating current circuit 26 is energized and is supplying a suitable current to the current responsive means 24, the

value of this current being below the predetermined minimum value required. to move the detent member 25 against the bias furnished by the associated spring. Since the switch is in the initial position, the test circuit is in an open circuit condition and as a result thereof the impedance of primary winding 28 of current control-- due to the relatively high voltage impressed on the electric valve means 6 under these conditions, upon closure of the test circuit 39 by the switch mechanism, each of the parallel branches of the test circuit will conduct a current of sufiicient magnitude to effect interruption of the parallel branches by means of fuses 33 and 35. By virtue of this circuit interruption, the current controlling means 21 is prevented from increasing the current supplied to the current responsive device 24 so that the detent member 25 is maintained in the position shown in the drawing. It is to be noted that under such conditions,.when the detent member 25 is in the position shown in the drawing, the latch member It cannot be released.

-' Inithe event a person seeks to obtain access to the electric valve means, such as electric valve V closed through a circuit includingfuse 33. stationary contacts 22 and movable contact l9, conductor 32-, electric valve means 8, conductor 34, stationary contacts 23, and movable contact 20, fuse 35, ground connection 3| and secondary 5 winding 29. When the secondary winding 29 is controlled in this manner, it eil'ects a material reduction in the inductive reactance of primary winding 28 to cause an increase in the current supplied to the current responsive means 24. By the proper arrangement of this circuit, under these conditions the current may be made to increase above the predetermined minimum value for which the current responsive device 24 is designed. This current of greater magnitude will attract the detent member 24, releasing the latch member I 6, The extension l8 of the operating mechanism l5 will then rotate the latch mechanism to permit the door l2 to be opened. The movable contacts I! and 2|! and stationary contacts 22 and 23 are maintained in engagement in the final position of the operating mechanism l5. To reclose the door and to reset the protective system, the operating handle I5 is maintained in the intermediate position so that the detent member is attracted to permit the latch member IE to be returned to the locking position.

Further desirable features of my invention are provided in that the system prevents a person from obtaining access to the high voltage el etrical apparatus in the event the alternating current circuit 26 becomes de-energized. Since the current responsive device 24 is designed to operate in accordance with a current of predetermined minimum value, the latch member IE is maintained in the closed or locked position under such conditions, thereby preventing access to the apparatus. Furthermore, by virtue of the test circuit which includes two parallel branches, the .protective system is arranged to prevent release of the latch member IS in the event the test circuit becomes defective. For example, if conductor 32 or 34 becomes disengaged from the electric valve means 6, the system prevents the release of the latch member it since the test circuit 30 must be completed through a portion of the electric valve means 6 and through both conductors 32 and 34. a While I have shown and described my inven-- tion as applied to a particular system of con- 0 nections and as embodying various devices diagrammatically shown, it will be obvious to those skilled in the art that changes and modifications may-be made without departing from my invention, and I, therefore, aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In combination, an enclosure having a door provided with a latch member, electrical apparatus within said enclosure, a detent member for engaging said latch member to prevent access to said apparatus through said door when said apparatus is subjected to a voltage above a predetermined value, and means responsive to the voltage of said apparatus for rendering said detent member inefiective so as to permit access to said apparatus through said door when said apparatus is subjected to a voltage of a value less than said predetermined value.

2. In combination, an enclosure having a door, electrical apparatus within said enclosure, means for preventing access to said apparatus through 'said door when said apparatus is subjected to a voltage above a predetermined value comprising a latch mechanism and a detent member for preventing movement of said latch member, and means responsive to the voltage of said apparatus for rendering said detent member ineifective so as to permit movement of said latch member when said apparatus is subjected to a voltage less than said predetermined value.

3. In combination, an enclosure having a door member, electrical apparatus housed within said enclosure, means for preventing access to said apparatus through said door when said apparatus is subjected to a voltage above a predetermined value comprising a latch member and a detent member, controlling means for said detent member to actuate said detent member to permit movement of said latch member, and a circuit interposed between said apparatus and said controlling means for testing the voltage of said apparatus and for controlling said controlling means so as to permit access to said apparatus through said door when said apparatus is subjected to a voltage less than said predetermined value.

4. In combination, a chamber having a door, electrical apparatus housed within said chamber, means for preventing access to said apparatus through said door including a latch member and a detent member being biased to prevent movement of said latch member, an electric circuit, and control means energized from said electric circuit responsive to a predetermined minimum value of an electrical quantity of said circuit for controlling the position of said detent member,

said control means being biased to prevent release of said latch member in the event said electric circuit becomes de-energized.

5. In combination, a chamber having a door, electrical apparatus housed within said chamber, means for preventing access to said apparatus through said door including a latch member and a detent member for preventing movement of said latch member, a source of current, control means energized from said source of current for controlling said detent member, and means for controlling said control means comprising a circuit interposed between said apparatus and said control means for testing the voltage of said apparatus, said circuit including two separate parallel branches, each connected between said apparatus and a point of reference potential and being arranged to be ineffective to control said control means in the event said branches become interrupted or in the event the voltage of said apparatus is above a predetermined value.

6. In combination, a chamber having a door, electrical apparatus housed within said chamber, means for preventing access to said apparatus through said door including a latch member and a detent member therefor, a source of current, control means connected to be energized from said source and being responsive to a current of predetermined minimum value for releasing said detent member to permit movement of said latch member, anwinductive device for controlling the current supplied-,to said control means and having one winding connected in series relation with said control means and a second winding for controlling the impedance of said one winding, and a circuit interposed between said apparatus and said second winding for testing the voltage of said apparatus, said circuit being arranged to short circuit said second of said windings to increase the current to said control means to a value above said predetermined minimum value when the voltage of said apparatus is below a predetermined value and arranged to prevent a decrease in the impedance of said one winding when said voltage is above said predetermined value.

7. In combination, a chamber having a door, electrical apparatus housed within said chamber, means for preventing access to said apparatus when said apparatus is subjected to voltages above'a predetermined value comprising a latch mechanism constructed to maintain said door closed, means for releasing said latch mechanism so as to permit access to said apparatus when said apparatus is subjected to a voltage less than said predetermined value including a source of current, a device responsiveto a current of predetermined value for operating said release mechanism, and means interposed between said,

source and said devi'ce and being responsive to the voltage of said apparatus for controlling the current in said device in accordance with the voltage of said apparatus.

8. In combination, a chamber having a door, electrical apparatus housed within said chamber, means for preventing access to said apparatus when said apparatus is subjected to a high voltage condition including a latch mechanism and a detent member for preventing movement of said door, and means for permitting access to said apparatus when the voltage of said apparatus is below said predetermined value pomprising a source of current, a current responsive device for operating said detent member to permit movement of said latch mechanism and a variable impedance means interposed between said source and said current responsive device for controlling the current in said device in accordance with the voltage of said apparatus.

9. In combination, a chamber having a door member, electrical apparatus housed within said chamber, means for preventing access to said apparatus when said apparatus is subjected to a voltage above a predetermined value including a latch mechanism and a detent member for preventing movement of said latch mechanism, a current responsive device for controlling said detent member to permit movement of said latch mechanism, and means for controlling the current in said device in accordance with the voltage of said apparatus comprising a source of current and a variable inductance interposed between said source and said device for controlling the current in said device in response to the voltage of said apparatus.

10. In combination, a chamber having a door, electrical apparatus housed within said chamber, a latch mechanism for maintaining said door in the closed position, an operating mechanism for releasing said latch mechanism, a detent member for preventing operation of said latch mechanism by said operating mechanism, a current responsive device for controlling said detent member, means for controlling the current through said device, a test circuit interposed between said apparatus and said current controlling means, and means including a switch controlled by said operating mechanism for controlling said test circuit, said test circuit being arranged to conaoeaa r? trol said current controlling means to prevent said current responsive device from actuating said detent member when the voltage of said' apparatus through said 'door when said apparatus is subjected to a voltage above a predetermined value comprising a latch member and a detent member, controlling means for said detent member to permit movement of said latch member, and a circuit including two separate parallel branches connected between said apparatus and a point of reference potential for testing the voltage of said apparatus and for controlling said controlling means to permit access to said apparatus through said door when said apparatus is subjected to a voltage less than said predeter= mined value.

12. In combination, a chamber having a door with a handle mounted thereon, electrical apparatus housed within said chamber, means for preventing access to said apparatus through said door when said apparatus is subjected to a voltage above a predetermined value comprising a latch member and adetent member for said latch member, controlling means for said detent member to permit movement of said latch member, a circuit interposed between said apparatus and said controlling means for controlling said controlling means, and a switch mechanism controlled by said handle for controlling said circuit, said circuit including two separate parallel paths connected between said apparatus and a point of reference potential and each including a current responsive device for interrupting said circuit in the event the voltage of said apparatus is above said predetermined value.

13. In combination, a chamber having a door, electrical apparatus housed within'said chamber, means for preventing access to said apparatus through said door when said apparatus is subjected to a voltage above a predetermined value comprising a latch member and a detent member for preventing movementof said latch member,

a controlling means for said detent member to permit movement of said latch member, a movvalue, a switch mechanism for closing said test circuit, said handle being arranged to effect closure of said test circuit through said switch when in said intermediate position and for effecting operation of said detent member to permit said handle to be moved to said final position to release said latch member when the voltage of said apparatus is below said predetermined value.

ELMO E. MOYER. 

